Breathe. Hold in your mind your view of what constitutes the most effective psychological therapy for acute depression. Try not to identify with your favourite therapy but simply observe it and let it be. Wish it well. And breathe again.

This was not the approach of the Cochrane Depression, Anxiety and Neurosis Group when it turned its attention to third wave cognitive and behavioural therapies (CBT) in a recent systematic review (Hunot et al, 2013).

One of the most ancient of techniques for dealing with suffering has become the most modern of psychological approaches for treating acute depression. Third wave cognitive and behavioural therapy refers to a family of treatment approaches to depression that all share the core aim of helping people to become aware of their thoughts and treat them in a non-judgemental way. These therapies differ from traditional CBT techniques in that their focus is on the process of thought, rather than engaging with its content. In many treatment contexts such techniques have displaced or complement traditional CBT approaches.

But is this enthusiasm for these new mindfulness based techniques warranted? Are these techniques as effective in reducing depressive symptoms – or better – than the techniques they are displacing? Are their effects as long lasting? And are people as willing to be given these sorts of treatment as they are to receive CBT?

Third wave cognitive and behavioural therapies aim to help people become aware of their thoughts and treat them in a non-judgemental way

Methods

Those hard-nosed Cochrane reviewers set about answering these questions by examining randomised controlled trials, of suitable quality, from Medline, EMBASE, PsycINFO and other databases which compared third-wave therapies to other psychological therapies, using two review authors to independently identify studies, assess trial quality and extract data.

Results

Three studies of acceptable quality were identified by the reviewers

Two studies (56 participants in total) compared an early version of Acceptance and Commitment Therapy (ACT) with CBT

Both ACT studies were assessed as being high risk for bias due to researcher allegiance, as the first author’s named supervisor in both was Dr Steven Hayes who developed ACT

Response rates for all three studies combined, using BDI or HAM-D scores, showed no difference in outcome for the third wave therapies compared with CBT (1.14, 95% CI 0.79-1.64). However, this evidence was deemed ‘very low quality’

There was also no difference in terms of acceptability of both treatments to the participants with similar drop-out rates for both groups of treatments (RR 1.12, 95% CI 0.47 to 2.67)

The two ACT studies also performed follow up measurements of clinical response at two months post-treatment which showed no significant difference between the ACT group and the CBT group (RR 0.22, 95% CI 0.04 to 1.15), though this finding was also deemed of ‘very low quality’

The review only included 3 studies, which were described as ‘very low quality evidence’

Conclusion

The authors preface their conclusions in this review with several remarks:

They note the small number of trials identified, and offer the possibility that some of the studies conducted recently may have been unpublished or sit in the grey literature (unindexed reports)

All three studies were conducted in North America and two were conducted before 1990, and are therefore of uncertain applicability to contemporary non-US settings

Most forms of third wave therapy were not included in the trials examined, including:

Mindfulness based cognitive therapy (although this may be used more widely in relapse prevention than in acute depression)

Meta-cognitive therapy

Compassionate mind training

Functional analytic psychotherapy

Many primary and secondary outcome measures that would be of interest – including measures of quality of life, adverse events or economic outcomes – were not included in analyses

There were no follow up measures taken in one study and the other two were limited to two months, thus making a judgement about the long term durability of the treatments difficult

The authors conclude that ‘very low quality evidence’ suggests that third wave CBT and other psychological approaches are equally effective and acceptable in the treatment of acute depression.

Given the rise of third wave therapies and their spread across UK mental health treatment services it is of integral importance to conduct further studies to determine whether these therapies really are better than CBT. Currently clinical guidelines recommend the use of mindfulness-based CBT (MBCT) as a relapse prevention intervention in those patients with a history of three or more episodes of depression, but there is growing interest in the use of MBCT for acute depression. Two registered trials comparing third wave therapies to other psychological therapies in major depressive disorder are therefore of considerable interest (NCT01070134), (NCT01517503).

The reviewers suggest that future studies should focus on:

Allocation concealment and blinding of outcome assessors

Treatment fidelity

Therapist qualification and experience

Researcher and therapist allegiance

The inclusion of acceptability outcomes, adverse events, quality of life and cost-effectiveness should also be include

There should be longer term follow up to establish the comparative durability of third wave CBT approaches to other psychological treatments

The review identified at least two ongoing trials that may soon add to the evidence-base in this field

Discussion

It is interesting to note how clinical enthusiasm can run ahead of the evidence base. While these newer therapies are intuitively appealing and anecdotal evidence of their success abounds, it is important that we do not let our desire to help people suffering with acute depression displace our dedication to providing care with a rigorous evidence base.

While signs do point to the efficacy of these new treatments, the field would be well served by studies that compare gold standard psychological treatments for depression against mature versions of third wave therapies. When clinical intuition is backed up by firm evidence we will know we are indeed heading in the right direction.

Happy and enthusiastic health professionals need to be sure that their clinical intuition is backed up by high quality research

Mark is a training psychiatrist from Australia who is completing a PhD, at King’s College London, regarding the link between stress and depression. He would like to understand the biological mechanisms underlying this connection and this currently involves torturing human neural stem cells in a dish with stress hormones and inflammatory molecules, and investigating the extent to which antidepressants and fish oils can reverse these effects. He hopes to contribute to reducing the burden of depression through clinical practice, research and public engagement. He recently won the national competition ‘I’m a neuroscientist get me out here’ which impressed his mum.